Studies on the effects of large fluid infusions on animals after oleic acid injection and hypovolemic shock to determine the factors which cause lung edema and death are being done in parallel with studies in sheep of the interstitial pressure and lymph oncotic pressure in animals resuscitated from shock with Ringer's lactate solution in an attempt to better define all factors in the Starling equation. Clinical studies of the effect of position and operative or traumatic injury on lung volumes and distribution of ventilation using ventilation perfusion measures and full chest image amplifier fluoroscopy with densitrometry measurements will be made. Dr. Paul Friedman has joined in this investigation in the studies of effects of position and chest cage injury on lung volume and density. Clinical studies to determine optimum ventilator treatment of acute respiratory insufficiency using intermittent mandatory ventilation and continuous positive airway pressure are continuing. These are based on the relationship between FRC, optimum pressure, shunt fraction and arterial partial pressure.